The present invention relates to a tubular body made of a thermoplastic resin as the matrix of the body, and a method of manufacturing the body, and more particularly relates to such a tubular body appropriate for a fishing rod, and a method of manufacturing the body.
A conventional method of manufacturing a fishing rod of a thermoplastic resin as the matrix of the rod was disclosed in the Japanese Patent Application No. 53890/83. In the method, a woven fabric made of reinforcing carbon or glass fibers as warp and a sheet made of a hard thermoplastic resin and softened by heating are overlaid and conjoined together under pressure to constitute a thin sheet, such thin sheets and polyethylene films are heated and stratified together to constitute a stratified sheet, the stratified sheet is tubularly shaped to constitute a tubular body including the carbon or glass fibers extending in the longitudinal direction of the body, and the body is shaped into a desired form for the fishing rod and finally reinforced with a room-temperature-setting resin and a fibrous material. Because of the method, the fishing rod is easier to form it and automate the manufacturing thereof and less in the difference of strength of the rod than a fishing rod made of a thermosetting resin. However, since the thin sheets each including the woven fabric and the thermoplastic resin sheet conjoined thereto under pressure are stratified with the polyethylene films, the amount of the resins of the former fishing rod is large and the ratio of the weight of the reinforcing fibers of the rod to that of the resins thereof is small. For that reason, the fishing rod is low in strength and rigidity and large in weight. Since the thin sheets are heated and shaped after the heating of the thermoplastic resin sheets, it is difficult to tubularly shape the stratified sheet. Therefore, the efficiency of the tubular shaping is low. Since the stratified sheet is tubularly shaped as it is heated, the reinforcing fibers are likely to be displaced to be nonuniformly distributed. Since the thermoplastic resin is solidified at the room temperature, it cannot be impregnated in between the reinforcing fibers as uniformly as the thermosetting resin for the latter fishing rod. For that reason, the former fishing rod cannot be made as high in elasticity and strength as the latter.
A fishing rod has a different-formed portion which serves as a grip, a reel rest or the like and at which the cross-sectional form of the rod sharply changes. In a method, the different-formed portion is made of a piece stuck to the other portion of the rod. However, the piece is likely to separate from the latter portion or become damaged and to deteriorate the appearance of the rod. In another method, the different-formed portion is made of a fiber-reinforced prepreg impregnated with a thermoplastic resin, wound on the body of the rod and then baked. However, the rod is likely to be damaged at or near the different-formed portion when an external impact acts to the rod.
The body of a fishing rod is made of a fiber-reinforced thermosetting resin, and a fiber-reinforced thermosetting resin is then piled on the body and cut into the external form of the rod to constitute a reel rest integrally conjoined to the body, as disclosed in the Japanese Patent Application (OPI) No. 224921/86 (the term "OPI" as used herein means an "unexamined published application"). However, since the thermosetting resin is used as the matrix of the rod, the reinforcing fibers thereof are likely to twist or meander at the time of the forming of the rod so as to lower the strength thereof before and behind the reel rest. Besides, it is necessary to take the trouble of cutting the piled resin.
If the fishing rod manufactured in the method disclosed in the Japanese Patent Application No. 53890/83 has such a different-formed portion, the reinforcing fibers are likely to meander or break at the time of heating formation so as to lower the strength of the portion and it is very difficult to form the portion.